As the Arctic continues to warm faster than the rest of the planet, evidence mounts that the region is experiencing unprecedented environmental change. The hydrological cycle is projected to intensify throughout the twenty-first century, with increased evaporation from expanding open water areas and more precipitation. The latest projections from the sixth phase of the Coupled Model Intercomparison Project (CMIP6) point to more rapid Arctic warming and sea-ice loss by the year 2100 than in previous projections, and consequently, larger and faster changes in the hydrological cycle. Arctic precipitation (rainfall) increases more rapidly in CMIP6 than in CMIP5 due to greater global warming and poleward moisture transport, greater Arctic amplification and sea-ice loss and increased sensitivity of precipitation to Arctic warming. The transition from a snow- to rain-dominated Arctic in the summer and autumn is projected to occur decades earlier and at a lower level of global warming, potentially under 1.5 °C, with profound climatic, ecosystem and socio-economic impacts.

随着北极变暖速度继续快于地球其他地区，越来越多的证据表明该地区正在经历前所未有的环境变化。预计整个二十一世纪的水文循环将加剧，开阔水域面积扩大导致蒸发量增加，降水量增加。耦合模型比对项目 (CMIP6) 第六阶段的最新预测表明，到 2100 年，北极变暖和海冰消失的速度将比之前的预测更快，从而导致水文循环发生更大更快的变化。CMIP6 中的北极降水（降雨）比 CMIP5 中增加得更快，因为全球变暖和向极地的水汽输送更大、北极放大和海冰损失更大以及降水对北极变暖的敏感性增加。北极在夏季和秋季从以雪为主向以雨为主的转变预计将提前几十年发生，并且全球变暖水平较低，可能低于 1.5°C，这将对气候、生态系统和社会经济产生深远的影响。